Subscription image transmission system and apparatus



April 3, 1951 E. M. RoscHKE SUBSCRIPTION, IMAGE TRANSMISSION SYSTEM ANDAPPARATUS Filed Sept. 13, 1947 l0 Sheets-Sheet 1 April 3, i951 E. MsRoscHKE 547,5

SUBSCRIPTION, IMAGE TRANSMISSION SYSTEM AND APPARATUS Filed septg 13,1947 10 Sheets-Sheet 2 Tq. Z

Positive Gaing I; Vertcn synch. Pulse Tune Consant Slightly Less ThonVert. ynh Pulse period Positive Going Vertical synch. I Tang. E Pulse AERw/N M. RoscHKE INVENTOR.

WZ@ H/s ATTORNEY pvl 3, 1951 E. M. ROSCHKE 2,547,598

SUBSCRIPTION, IMAGE TRANSMISSION SYSTEM AND APPARATUS Filed Sept. 13,1947 l0 Sheets-Sheet 3 q [60 #al /55 L /469 Y .f /47 l 7:1-, l /40 /4//79 T04 /ao 49 52 D'eentiating Clrcmts Vert. nch. Pulse v Pearocy 6/ TagE width EMI ERw/N M. RoscHKE INVENTOR.

H/s ATTORNEY PIIi 3 1951 E. M. Roser-IKE 2p?,

SUBSCRIPTION, IMAGE TRANSMISSION SYSTEM AND APPARATUS Filed sept. 13,1947 i0 sheets-sheet 4 ff ,254 ifi T E Tuner I And Deiectol' sgnolorInvert@ r Hon x pero SWAC, SweEP v rt. V Plse l l Relay Gate Current I:3 Swich Frs. 5

I"==-/ f4 1 Verheul l U Yoke 6.? Qeverama Relay \.62 sharply CQ- 6 T nedLPL #5 8; Red.

.9 3 [rtv/,64 S'Feech Cenh-al pass .bL, swmh 263 1:, lie, Z/ Boavd lERw/N M. Rosal-IKE 262 IN VEN TOR.

BY OW pr 3, NSI E. M. RoscHKE SUBSCRIPTION, IMAGE TRANSMISSION SYSTEMAND APPARATUS 10 Sheets-Sheet 5 Filed Sept. 13, 1947 E .r l

ERw/N M. RoscHKE IN V EN TOR.

Hfs Afname? Pl'-S, 1951 E. M. RoscHRE 54?,5

SUBSCRIPTION, IMAGE TRANSMISSION SYSTEM AND APPARATUS Filed Sept. v1:5,1947 l0 Sheets-Sheet 6 Iig-I1 ERM/m M. RoscHKE JNVENToR.

Hfs ATTORNEY April 3, ESSE E. M. RQSCHKE 2,54%5

SUBSCRIPTION, IMAGE TRANSMISSION sYsTEN AND APPARATUS Filed sept. 13,1947 l0 Seejts-Sheet 7 ERw/N M, Roscmrs INVENToR.

IH/s Arronwev E. M. RSCHKE Apri 3, i951 as SUBSCRIPTION, IMAGETRANSISSION SYSTEM AND APPARATUS 10 Sheets-Sheet 8 Filed sept. 13, 1947ERw//v M. Rose/msv INVENTOR.

H/s AroR/VEY April 3, i951 E. M. RQSCH'KE 25479593 SUBSCRIPTION, IMAGETRANSMISSION SYSTEM AND A.APPARATUS Filed sept. 1s, 1947 1o sheets-sheet9 A T lci l5 255 60 54 25? 2661' ,257 Tuner' Vdl i And A' e? I LDetector "1P 5,5 59 synch. Vert. Signal Sweep Separatr Drive /4 ToneFrequeny 299 Filter And Switch (j: Operator Fig. I4 285mg 25% /55290 A gDeglfqdLme 25.? SHOHL wee Swltch Drive? Fyg. l5 l S eech 26? "-1 FilterU l Z/ Central -43 262 Switch Board ERw/N M. RoscHKE INVENTOR.

April 3, w51

Filed Sept. 13,*1947 y E. M. Rosen-IKE SUBSCRIPTION, IMAGE TRANSMISSIONSYSTEM AND APPARATUS ERw/N M RoscHKE INVENTR.4

Hfs ArroRNEY Patented Apr. 3, 1951 SUBSCRIPTIN IMAGE TRANSMXSSION ISYSTEM AND APPARATUS Erwin M. Roschke, Chicago, Ill., assigner to ZenithRadio Corporation,

illinois a corporation of Application September 13, 1947, Serial No.773,848 y 23 Ciaims.

This invention relates to image transmission systems of the subscribertype and more particularly to such systems as are disclosed and claimedbroadly in the copending application Serial Number '742,374 of AlexanderElett et al. entitled Radio-Wire Signalling System, Iiled on April 18,1947, which has now issued to Patent No. 2,510,046, May 30, 1950, andassigned to the same assignee as the present application.

In that copending application the system is claimed for the transmissiontc subscribers only7 of a complete signal, part by radio broadcast andpart by wire line conductor, which complete signal may be utiized in thesubscriber-s receiver to produce a complete usable picture. The wireline conductor may conveniently be a telephone line or a power line andsome arrangement is provided in connection with that conductor whereby arecord is kept of the time when` the subscription signals are utilizedby the Subscriber so that he may be charged therefor. In the case of the`telephone line, an operator may make suitable connections to transmitthe required part of the signal over the telephone system to theindividual subscriber and may record a charge therefor, or in a dialsystem such charge may be automatically recorded. In a power line systemsuitable meters may be provided, preferably located so that they can beread simultaneously with the usual power meter, to indicate the periodof use of that part of the signal coming over the power line.

It is within the broad concept of that matter claimed in such copendingapplication that the part oi the signal which is transmitted by Vradiobroadcast shall be insuflicient to reproduce a proper picture un`ess theremaining part of the signal which can be received only by the wire lineis utilized with the part received by radio broadcast.

It is an object of this invention to provide a particular system of thatgeneral type in which that part of the signal received by radiobroadcast alone produces a picture which is moved recurrently back andforth in the vertical or horizontal direction so as to be viewable onlywith great difficulty unless such motion is cancel`ed out by appropriatesignal received by wire line conductor.

The features of the present invention which are believed to be novel areset forth with particularity in the appended claims. The presentinvention itself, both as to its organization and manner of operation,together with further Yobjects and advantages thereof may best beunderstood by reference to the following description taken in connectionwith accompanying drawings in which:

Figure 1 illustrates one form of image transmitter arranged according tothe invention;

Figure 2 through 8 illustrate certain detailed circuit arrangementsforming portions of Figure 1;

Figure 9 illustrates an image receiver arranged especially foroperationwith the embodiment of Figure l;

Figure 1D illustrates an alternative form-of image transmitter arrangedaccording to the invention Figures 11, 12 and 13 illustrate certaindetailed circuit arrangements forming portions of Figure 10; f

Figure 14 illustrates an image receiver Yarranged especially for usewith the image transmitter of Figure 10;

Figure l5 illustrates a detailed circuit arrangement forming a portionof the image receiver of Figure 14; and

Figure 16 illustrates certain characteristics of` receivedand reproducedfrom only that part of.

the signal which is radio broadcast to move back and forth in ahorizontal direction,and the other being to cause such an ima-gerecurrently to turn upside down and right side up. That part of thesystem of Figure 1 which causes such image recurrently to move back andforth is within the scope of the present invention. More specically inthis arrangement the time of scanning in the horizontal direction'isrecurrently altered with respect to the transmitted synchronizingsignals and the alternation between the normal transmission of the imageand the transmission with such alterations in scanning time issufficiently rapid that, even if the user of a receiver Without theproper signals received over wire line conductor should know just howthe alteration is made, it would be most diicult to switch back andforth between the normal system and the altered system of transmission.Accordingly, with such a system it is highly desirable from thestandpoint of the person who wishes to view the image to pay therequired fee and obtain the information necessary from the appropriatewire line conductor to realter the signals at the proper time so as toreceive good picture service.

While, as illustrated, the alteration between 3 normal picture signaltransmission and transmission with inverted scanning direction andaltered scanning time is accomplished at such times as the televisioncamera is being moved across a scene or at such times when a change ismade from one television camera to another, as when the` scene is to bechanged, the alteration in scanning-'time of horizontal lines may bemade in accordance with the present disciosure at any desired timechosen entirely at random.

In Figure l a 'television camera Ii) isprovided with the usual lenssystem II and iconoscope or image orthicon I2 from which video signalsare transferred through conductors I3 to a video amplier I4. v Ampliedvideo signals are then transmitted from video amplier I4 through asynchronizing signal and pedestal mixer I5, a background reinsertiondevice I3, and a carrier wave generator and modulator I1 to an antennaI8 from which they are radiated. In other words, the video signals whichappear in conductors I3 are treated in an entirely normal fashion, andnormal synchronizing signals and pedestals from a vertical andhorizontal sweep and synchronizing signal generator I3 are mixed withthose video signals in quite normal fashion in the mixer I5, so that thesignal radiated from the antenna I8 appears to be quite normal unless itis attempted toreproduce it as a picture. Actually, the video signalswhich appear in conductors I3 are altered by special alteration'of thevertical sweep signals which are impressed on the vertical yoke coils 2Bassociated with the iconoscope I2, and by special alteration of thehorizontal sweep waves which are impressed on the horizontal' sweepcoils 2l associatedfwith the iconoscope I2.

In order that the appropriatealterations are made at the desired time, asnap switch 22 is provided on the supporting base 23 for the camera Ill,arranged so that, when the camera is being or has'beenturned in onedirection, a .conductor 24 is grounded and, when the camera is being orhas been turned in the other direction, a negative potential isimpressed on conductor 24. For this purpose, ther camera base 23supports a shaft 25 for rotation therewithin, the camera I3 beingsupported on the shaft 25. A collar 26 surrounds the shaft 25 and restsbetween the upper surface of the base 23 and a collar 21 integral withthe shaft 25, the collar 23 being arranged always to turn with thecamera and shaft 25 until a stop projection 28 on the collar 23 engagesone or the other of two spaced stops 29. The switch 22 includes a movingcontact member 30 supported at its lower end on the base 23 and bea-ringagainst one end of the spring 3|, the other end of which presses againstthe stop 28 on collar 2E. Suitable fixed contacts 32 and 33 aresupported on base 23 on either side of the movable switch member 3l). Inconsequence of the toggle action of the movable switch member 33 andspring 3I, member 30 always rests against one or the other of the fixedcontacts 32 and 33. One of the switch contacts 32 is grounded and theother is connected to a suitable source of negative potential.

For the purpose of making the alteration between normal transmission ofthe television picture signal and the above described alteredtransmission each time when transmission is switched from one camera toanother, a special switch arrangement is provided in connection with thecamera switch, which is arranged to change the connections of conductorsi3 from one camera to another, so that it also reverses the connection 4with ground and negative potential to the two contacts 32 and 33. Thecamera switch 34 has an operating handle 35 which is connected with adouble pole double throw switch 36, one movable blade of which isgrounded and the other movable blade of which is connected to thenegative terminal of the source 31 of biasing potential, the positiveterminal of which source is grounded. The four fixed contacts of thedouble pole, double throw switch 33 are connected in usual fashion tothe two contacts 32 and 33 so that upon each operation of the cameraswitch operating handle 35, the connections to ground and to thenegative terminal of source 31 are reversed between contacts 32 and 33.

In consequence, the connection of conductor 24 is alternated betweenground and the negative terminal of source 31 each time when the cameraswitch is operated, and also each time when the camera Ii), which is atthe time in use, is turned.

It ris also preferred that the change fromv normal transmission toalternate transmission takes place during the transmission of thefirstvertical or frame impulse after operation of the camera switch 34or turning of the camera to operate switch 22. For this purpose,conductor 24 is connected with a vertical pulse gate and tone frequencyoscillator switch 38, to which positive going vertical synchronizingpulses are transmitted through conductors 39 from the vertical and horizontal sweep and synchronizing signal generators I9. The verticalpulse gate 38 is arranged to produce a control voltage only during thesimultaneous existence of a positive going vertical synchronizing pulsereceived from conductors 39 whenever conductor 24 is grounded.

A tone frequency oscillator 43 is connected through conductors 4I to thevertical pulse gate and tone frequency oscillator switch 38 so that inthe absence of the aforesaid control voltage the s tone frequencyoscillator 43 is caused to operate and produce a sine wave key signal,termed tone frequency for convenience. Tone frequency oscillationsproduced by the oscillator 4! are sup,- plied `through conductors 42 toa telephone line extending to a central switchboard 43.

The tone frequency oscillations from oscillator 40 'are also suppliedthrough conductors 44 connected with conductors 42 to a sharply tunedamplier and rectifier 45, this amplifier being tuned with suiiicientsharpness as to prevent the transmission through it of substantially allfrequencies except that lations from oscillator 4G. In addition, therectifier 45 is provided with a load circuit, the time constant of whichis greater than the period of the tone frequency oscillations fromoscillator 4!) and the rectifier output is transferred throughconductors 43 to a vertical pulse gate '41 which, whenever oscillationsare produced by oscillator 40 and tuned, amplified and rectiiied bytherectifier ^45, causes vertical pulses received from the vertical andhorizontal sweep and synchronizing signal generator I9 throughconductors 43 to be transferred through conductors 49 both to afrequency divider 53 and a relay current switch 5I. The vertical pulsessupplied through conductors 48 to the gate 41 are positive going andappear as negative going vertical pulses in conductors 43. The frequencyof these pulses is divided a suitable number of times by frequencydivider 53 to a rate which will prove objectionable when-used to causealteration of the transmitted pictures during the intervals when suchalterations are being caused.

of the tone frequency oscil- The lower frequency pulses lproduced by thefrequency divider are transferred through conductors 52 to an inverterswitch 53, which operates to advance or delay, under the control of thepulses received through conductors 52, the production of horizontalsweep signals which are impressed on the horizontal sweep coils '2l ofthe camera i5. To this end, horizontal synchronizing pulses aretransferred through conductors 54 from the vertical and horizontal sweepand synchronizing signal generator IS to a delayed blocking oscillator55 and then through conductors 56 to the inverter switch 53, the outputpulses of which are inverted or not inverted according to the presenceor absence of a pulse received by way of conductors 52. The outputpulses from the inverter switch 53 are transferred through conductors 51to a horizontal sweep blocking oscillator 58, whose output drives aconventional horizonte-.l sweep drive 59 which is connected throughconductors 6D to the hori-l Zontal sweep coils 2| of the camera Il).

In consequence of this arrangement, during certain intervals the cameraswitch 34 and the camera turning switch 22 cause pulses not to appear inconductors 52, during which interval the inverter switch 53 does notoperate and normal horizontal sweep signals are transferred throughconductors 60 to the horizontal sweep coil-2| in camera I5. when thecamera switch 34 and the camera turn switch 22 so provide, pulses appearin conductors 52 and, under control kof those pulses, the hori- Zontalsweep voltage delivered to the horizontal sweep coils 2l of camera ISthrough conductors 60, is advanced or delayed in time a predeterminedamount, which is preferably relatively small compared to the time periodof one horizontal sweep and retrace. The result during those intervalsis that the video signal produced by camera I0 on conductors I3 is, ineffect, alternately advanced and retarded in time with respect to thehorizontal synchronizing Apulses and pedestals mixed with it in mixeri5, and it is quite diicult during those intervals to adjust a receiverto correct for such alternate advance and retard in the time oftransmission of video signals, and even more diflcult to anticipatetimes when such alternate advance and retard in the sweep current is tobe started or stopped.

Pulses impressed by the vertical pulse gate lll on conductor 49 are alsoimpressed on relay current switch 5l which, in the presence of pulses onconductors G9, causes current to flow throughconductors BI connectedwith a vertical yoke reversing relay 62. The relay 62 is arranged merelyto reverse the connection lbetween its input conductors 63 and theconductors ed which are arranged to deliver the vertical sweep pulses onconductors 63 to the vertical sweep coils 20 in camera I0. f

In consequence, when the vertical yoke reversing relay 52 is operated toreverse the connections between conductors 53 and 54, the transmittedpicture is scanned in an inverted fashion so that a normal receiverwould reproduce the picture upside down. This rapid reversal of thepicture in the receiver from rightside up to upside down makes thedifficulties of correction even greater, particularly since thosealternate reversals take place only during intervals when pulses appearon conductors 52.

The relay current switch 5! and the inverter switch, 53 are arranged, asis described herein- In the alternate intervals i lations from each of 6after, in the following gures where -specic cil"' cuits are illustrated,so that they always leave the picture right side up and with normallytimedvsynchronizing pulses during those inter-v n vals when normaltransmission is being produced.

It is important to note in connection with this arrangement that thecomplete television siga nal includes a program signal and a key signal,the program signal being transmitted by radio broadcast and the keysignal by wireline conductor only. The key signal is actually the in=formation transmitted by the alternate presence and absence'of tonefrequency oscillations on the wire line conductor 42. The program signalis that which is transmitted by radio broadcast and is not properlyreproduceable without the key signal for which a subscriber must pay.

In order Athat the tone frequency oscillations which represent the keysignal and are impressed on conductor 42 shall not interfere in any waywith normal telephone service, it is desirable that the tone frequencyoscillations be arranged not to be reproduced in telephones connectedwith the central switchboard43. For that purpose it is preferred eitherthat the tone frequency oscillations be outside the audio-frequencyrange normally used by the telephone sets, suitable filters beingprovided to insure separation of the tone frequency oscillations of thetelephone line and audio-frequency signals normally used betweentelephone sets, or that a single frequency be used within theaudio-frequency range of relatively low level and suitable lters beprovided to prevent a very narrow band of frequencies 'around thatsingle frequency from operating the telephone set.

It is quite usual that telephone systems are constructed with restrictedfrequency pass bands in trunk lines connecting main and sub-stationswitchboards. Consequently, the transfer of tone frequency oscillationfrom the oscillator do through the telephone line to the centralswitchboard 3 and then through such a trunk line to a suburbanswitchboard 65 may be difficult or impossible. While it is possible toadjust thefrequency of the oscillator 4G so that it lies within thesignal range of the ordinary telephone system, and to provide suitablerejection filters in the telephone system very sharply tuned to rejectonly the frequencyI of oscillations from the oscillator-45, it ispreferred to provide a special line 65 between such switchboards 43 and`B5 as may normally have trunk lines extendingtherebetween withrestricted frequency character istics. With such a special line 65,control osciland may also make the appropriate charges to persons whowish to receive the proper tone'frequency oscillations, properly timed,from the television transmitter.

In the operation of such a transmitter as is illustrated in Figure l,one caution should be observed particularly. WithV an ordinaryiconoscope in the camera IQ, special shading voltages are normallyrequired to correct the video signals appearing on conductors I3. Theseshading voltages are dilferent when the picture is altered by turning itupside down. However, if an orthicon type picture pickup tube is used,substantially no change in shading is necessary. Similarly, an ordinaryiconoscope requires a keystoning correction which must be reversed whenthe picturel is turned upside down, whereas the orthicon type picturepickup tube requires no keystoning voltage.

In Figure 2 the vertical pulse gate and tone frequency oscillator switch38 and tone frequency oscillator 4E] are shown in detail. The conductor24 is connected to the rst control electrode 81 of an electron dischargedevice 68 arranged as a gating switch. The cathode 89 is groundedthroug-h a biasing resistance 19, the screen electrode 11 is connectedto the positive terminal of the source 12 of operating potential, thenegative terminal of which'source is grounded, and the anode 13 isconnected througha load resistance 14 to the positive terminal of source12. The second control electrode 15 is connected through a gridvresistance 16 to the negative terminal of source 11 of grid biasingpotential, the positive terminal of which is grounded. The second con-ltrol electrode 15 is also coupled through a cou- 13o1ing condenser 18 tothe -ungrounded conductor At all times when the conductor 24 ismaintained at a negative potential, discharge current through device 98is cut off and the anode 13 remains at a positive potential, regardlessof the potential of control electrode15. However, when the conductor 24is grounded, control electrode 15 is recurrently changed in potentialpositively sufficient to cause the device 83 to conduct icurrentduringthe presence of positive going vertical synchronizing pulses onconductors 39. When device 88 conducts current, the anode13 recurrentlytherefore produces corresponding negative pulses of potential. The anode13 of device 68 is connected through a coupling condenser 19 to theanode of an electron discharge amplifier device, whose control electrode81 is grounded and whose cathode 82 is connected through a couplingcondenser 83-to the ungrounded conductor 39, and whose cathode 82 isalso connected to the cathode 84 of another electron discharge device85, the two cathodes being connected in common through a resistance 86to ground. The anode 89 isjalso connected through a load resistance 81to the positive terminal of source 12 and is also connected through acoupling condenser 88 to the control electrode 89 of device 85, a gridresistance 90 being connected between control electrode 89 and cathode94. The anode 91 of device 85 is connected through a load resistance 92to the positive terminal of source 12, and is y also connected through aresistance 83 to the con-- trol electrode 94 of an electron dischargedevice 95 arranged to operateas a switch. Control electrode 94 of device95 is connected through a resistance 96 to the negative terminal of asource 91 of biasing potential, the positive terminal of which source isgrounded. The anode 98 of the device 95 is connected directly tothe-positive terminal of source 12 and the cathode 99 of device 95 isconnected directly to the control electrode 1D0 of an oscillatingdischarge device 18 i. Cathode 99 and control electrode 108 are alsoconnected to one terminal of an inductance 102 whose other terminal isgrounded, a condenser 1,93 being connected in parallel with inductance102 lto form a'circuit tuned to resonate at the desired tone frequency.A tap on inductance 162 is connected with the cathode 194 of theoscillating device 101, whose anode 105 is connected directly to thepositive terminal of source 12. Y

An inductance coil 198 is magnetically coupled with the inductance 102and is connected between conductors 42 so that tone frequencyoscillations r non-conductive and memes' whenever produced by theoscillating device 101 and the resonant circuit 102 and 1113 rareimpressed on conductors 42.

As pointed out, when device 88 is conducting.

so that anode 13 and control electrode 89 are at flow between anode 88and'cathode 82. So long-A as device remains conducting, during the timewhile conductor 24 is negative, its anode 91 remains at a relatively lowpotential and the potential of source 91 is suiiicient that controlelectrode 94 of device 95 maintains device 95 in nonconductivecondition. During such times, the oscillating discharge device 191produces continuous tone frequency oscillations whichY are transmittedover conductors 42. l

During other intervals while conductor 24 is at` ground potential,negative potential pulses appear on anode 13 which tend to make device85 to maintain current flow between cathode 82 and anode 88. Asindicated by th'e labelI Time constant slightly less than verticalsynchronizing pulse the coupling condenser ,88 with its associatedcircuit elements has va'tirne'constant such that device 85 during thistime remains out oif for all intervals except extremely small intervalspreceding each vertical pulse. Therefore, for all such intervals whendevice 85 is cut off device 95 conducts current heavily, anode 91 beingmaintained substantially-at the potential of the positive terminal ofsource 12; and the oscillating discharge device 18! remainssubstantially inoperative except for such very small intervalsimmediately preceding this vertical pulse; These intervals areso smallthat the tuned circuit 182, 193 has no time to build up any appreciableoscillation. Consequently during the intervals that the conductor 24 isgrounded. no appreciable tone frequency signal is transmitted overconductors 42. Y Y

In Vthe arrangement ofl Figure 2, therefore, whenever the potential onconductor 24 rises to ground potential, at the time of the nextsucceeding positive Y going vertical synchronizing pulse on conductors39 the tone frequency oscillator including tuned circuit 192, 193 ceasesoperation. Thereafter, following the appearance or a negative potentialonconductor 24 and at the time when the next succeeding positive goingvertical synchronizing pulse appears on conductors 39, the tonefrequency voscillator again begins oscillation and continuestransmitting the tone frequency on conductors 42 until the potential onconductor 24 again rises to ground potential,

Figure 3 illustrates the circuit arrangement of the tuned amplifier andrectifier 45, and the vertical pulse gate 41. `This gate, in thepresence of tone frequency oscillations on conductors 44, which, asshown in Figure l, are connected with conductors 42, transfers positivegoing vertical synchronizing pulses from conductors 48 to conductors 49,and prevents. such transfer when tone frequency oscillations are notpresent on conductors 44. For that purpose an inductance 191 isconnected between conductors 44 and is coupled ymagnetically with aninductance 188 in shunt with a condenser 199 to form a resonant circuittuned to the frequency of the tone frequency oscillation. The controlelectrode 111! of an electron discharge amplifier device 1 1 1 is--coninthe` presenceoi a negative going edge of a pulse between conductors 9,the control electrode |42 is forced momentarily in `the negativedirection. The same thing isY true of the condenser |55 and theresistances associated with it.

Assuming that, to begin with, discharge device |43 is conducting,cathode iM is at a substantially positive potential with respect toground Aand anode |51 is at a minimum positive potential. The voltagedivision produced across resistances y |58 and |53 is made to causecontrol electrode |52 of device l5! to cut off current pulses throughthat device. In that condition, the negative bias voltage betweencathode |50 and control electrode |52 is made suiiciently far beyondcutoi ispimpressed on control elec.rodes It and |52,y

while the increased negative potential on control electrode |52 doesnothing, the negative potential on electrode |2 tends to reduce currentflow through device N3, thereby reducing the positive potential ofcathode Util and increasing the positive potential of anode |555. Byreason ci the cross-connection, the potential of Ycathode |59 at thesameA time becomes less positive and the potential of control electrode|52 becomes less ngative so that current begins to flow through device|5l, the anode |54 of which drops in potential and by reason of couplingcondenser |t| causes the potential of control elecn'ode |42 to becomestill more negative. This process accelerates until device |43 no longercarries current and all of the current is carried by device |5|. Thiscondition continues until the next succeeding negative poternial impulseis impressed on control electrodes |i|2 and |52, at which time thereverse action takes place to make device |43 conductive and device iiilnon-conductive. In consequence, the potential of anode |51! bee comesmore positive following one negative potenlial pulse impressed oncontrol electrode W2. It is therefore apparent that the frequency of thewave appearing on anode |55 is just onehalf that of the pulses appearingon conductors A second frequency division is carried out by twosucceeding electron discharge devices |62 and |53 connected in similarfashion. 'The anode Hit of device |62 is connected 'through a pair orresistors |55 and |66, in series, to the anode itil' of device |63. Aresistor |68 is connected between the positive terminal of source lasand a point betweenresistances |55 and |55. i5@ of device I5! isconnected through a coupling condenser |6 to a point between resislances|55 and |66. Cathodes |10 and 11| of discharge devices |62 and |63,respectively, are connected together and through a resistance V52 toground. The control electrode |13 of device l? is connected through agrid resistance |15 to ground and through a parallel combination ofresista; ce |15 and condenser |15 to anode |51 of device |63. Similarly,the control electrode il? of device At the same time, an

|63 is connected through a g'rid resistance i'l K to ground and througha parallel combination o resistancenll and condenser to anode |64 ofdevice |62. Y I

The time constant of condenser |59 andthe associated resis.ances, asindicated by the label Diierentiating circuits is made suiiicientlYsmall that only the leading and trailing edges of waves appearing onanode iElli of device |5| are impressed across resistance |68 and hencethrough resistances |65 and liit, respectively, on control electrodes|11 and |13. These leading and trailing edges are impressed on controlelectrodes |13 and |11, in the form of alternately positive and negativegoing short pulses which operate on discharge devices |52 and |63 in afashion similar to the operation of devices |43 and |5| so that there`appear on the anode |61 of device |63 waves whose frequency is halfthat of the waves appearing on anode |541 of device |5| and o nlyone-quarter of the frequency of waves between conduc-ors 4t. One of theconductors 52 is grounded and the other connected directly to anode |61so that these waves of one quarter frequency appear between theconductors 52.

For the purpose of assuring, when waves disappear between conductors 4Safter the vertical pulse gate 41 stops transmission of vertical pulses,that the discharge devices |62 and |63 will be maintained in a desiredvoltage condition between conductors 52 so that the inverter switch 53during those times will remain in the proper condition, a suitable pulseis impressed on control electrode |11 through a pair of conductors iciconnected from the relay current switch 5| as shown in Figure 1. One ofthe conductors |81 is grounded and the other is connected through aseries arrangement of resistance |82 and condenser |83 to controlelectrode |11. The condenser |83 with its associated resistances is madeto have a short time constant, as indicated by the label Diferentiatingcircuits in order that alternately recurrent short positive and negativepulses are impressed from conductors i3! on the control electrode |11.

In Figure 5 conductors 49 (shown in Figure 1 as being connected with thevertical pulse gate 1) impress negative going vertical pulses on therelay current switch 5| which includes two electron discharge devices|84 and |65. One of the conductors 4|) is grounded, and the other isconnected through a coupling condenser |88 to control electrode |29 ordevice |85. Anode |81 is connected through a load resistance |90 to thepositive terminal of a source lili of operating potential, the negativeterminal of which source is grounded. The control electrode |92of device|313 is grounded .and its cathode |93 is connected directly with thecathode |94 of device |85, both cathodes being connected in commonthrough a resistance |65 to ground. Control electrode |89 o device |85is connected through a grid resistance |95 to the cathodes |33 and 19d.The anode |91 of device |85 is connected to one of two conductors ti,between which the coil of the vertical yoke reversing relay isconnected, the relay being shown in Figure 1 as rectangle 62. The otherof the conductors 6| is connected to the positive terminal of sourceBSI. Y

In the absence of vertical pulses between conductors dil, device |85remains conductive and device it non-conductive, so that currentcontinually iiows through conductors 5| from source |t|. Upon theappearance of negative going gated vertical pulses between conductors49, and on control electrode |69 of device l85g`current conductionthrough device |S5 begins to decrease 'H5 of device IH nected with oneterminal of the tuned circuit |08, |09, the other terminal of whichtuned circuitis grounded and also connected to cathode H2 of device ithrough a parallel combination of biasing resistance H3 and Icy-passingcondenser II4. The anode H5 of the device III is connected to oneterminal of an inductance H5, the other terminal of which is connectedto the vpositive terminal of the source H7 of operating potential, thenegative terminal of such source being grounded. A tuning condenser H8is connected in shunt with inductance I i t to form a circuit resonantto the tone frequency oscillation. It is desirable to make both thetuned circuit- !58, |39 and the tuned circuit H8, H6 of good quality sothat several cycles of the tone frequency are required to build upsubstantial alternating potentials in those circuits. In order toprevent device IH from responding to very small potentials appearingacross conductors 44, av resistance H9 is connected between cathode H2andthe positive terminal of source II'E to maintain a xed yminimum biasbetween cathode H2 and control electrode H, so that device III 'will notamplify very small potentials. With Asuch an arrangement, extraneousnoise voltages appearing across conductors 44 or very short bursts ofweak intensity oscillation from device 95 of the vertical pulse gate andtone frequency oscillator switch 38 (Fig. 2) are not reproduced in thetuned circuit I |5, I I8 to cause false operation of the circuitarrangement.

The amplified oscillations appearing on anode are transferred throughcon- |2f3 to the anode |2| of a rectifying discharge device |22, whosecathode |23 is con- .nectd through a resistance |24 to ground. Acondenser is connected in parallel with the resistance 524 andaresistance |25 is connected between anode |2I and ground so that device.|22 rectifies tone frequency oscillations appearying on anode H5 and inresponse thereto develops across resistance |24 a continuous potentialwhich is positive with respect to ground.

denser The ungrounded terminal of resistance |24l is connected directlywith the rst control electrode |27 or" an electron discharge device |28whose cathode |23 is connected through a biasing resistance |32 toground. The cathode |29 is also connected through a resistance I3! topositive terminal of source H7 so as to maintain cathode |29 at a xedpositive bias with respect to the iirst control electrode |27 and thesecond control electrode |32 of device |28. It may be here noted thatthe connection between the upper terminal of resistance |24 and firstccntrol'electrode |27 one of the conductors 45 illustrat in Figure l,while the connection between 'ound and the other terminal of resistanceis the other of conductors 45 of Eigure l.

One ci the conductors 48 (shown in Figure l) is grounded and the otheris coupled through a condenser to the second control electrode i552 ofdevice |23, the control electrode IZ being also connected through a gridresistance |34 to ground. The screen electrode |35 of device |23 isconnected through a .by-passing condenser |36 to ground and through aresistance I3? to poitire terminal of source |`J to maintain the screenelectrode at a fixed positive potential with re'pect to cathode 25. Theanode |58 of device |25 is connected directly with one of the conductors49, other of which is grounded, and the anode |38 is also connectedthrough a load Lil resistance |39 to the positive terminal of source H7.

When a continuous positive potential appears across resistance |24 inthe presence' of tone frequency oscillations on conductors 44, so as tomake control electrode |27 positive with respect to ground, cathode I 29is also a positive potential with respect to ground, but not at asuiciently positive potential to maintain device |28 cut orf if thesecond control electrode |32 were also at a positive potential. However,the bias voltage across resistance -I3!! is suicient even when controlelectrode |27 is positive with respect to ground, to 'maintain currentilow through device |28 cut oilc so long as control electrode |32remains at ground potential.

Consequently, voltage pulses appear on anode |38 of device |28 only whentone frequency oscillations appear on conductors 44, and even then onlywhen positive going vertical synchronizing pulses from conductors 48 areimpressed through coupling condenser |33 on control electrode |32. Thesevertical synchronizing pulses appearing between conductor 48 appearsonconductors 44.

Figure 4 illustrates in detail the circuit arrangement of the frequencydivider 50 shown in Figure 1. In this divider the properly gatedvertical pulses from the gate 47 appear and are changed in frequency toproduce a higher or lower frequency pulse which can be used to producethe most objectionable recurrent alterations in the picture during thetime when a tone frequency signal appears on conductors 42 in Figure l.In the example illustrated in Figure 4, the vertical pulse rate isreduced in frequency by dividing the original vertical pulse frequencyin half twice. For this purpose the ungrounded one of conductors 49 iscoupled through a series combination of a condenser |42 and a resistance|4| to thercontrol electrode |42 of a discharge device |43, whosecathode |44 is conneced through a resistance |45 to ground. The controlelectrode |42 is connected through a grid resistance |46 to ground andthe anode |47 of device |43 is connected through a suitable loadresistance |48 to the positive terminal of a source |49 of operatingpotential, the negative terminal of which source is grounded. Cathode|44 is also connected directly to the cathode |58 of a second electrondischarge device I5I, whose control electrode |52 is connected through agrid resistance |53 to ground, and whose anode |54 is connected througha load resistance |55 to the positive terminal of source |49. Thecontrol electrode |52 is also connected through a series combination ofa condenser |55 and a resistance |57 to the ungrounded one of conductors49. Anode tween conductors 4S control electrode |42 is moforced in thepositive direction, while mentarily on conductors 49y Vtial and device|84 begins to 13 with the result that cathode l|94 drops inpotenconduct, with anode |87 also dropping in potential and, beingcoupled through condenser |88 with control electrode |89, consequently,Treducing the potential of control electrode |89 still further. Thisprocess is continued until device |85 no longer conducts current and thedevice IBA is fully conductive.

As indicated by the label Time constant slightly less than verticalsynchronizing pulse period the condenser |88, together with associatedresistances must maintain the control electrode |89 suciently negativewith respect to cathode |96 that the devicek |85 does not conductcurrent until a time just prior to the appearance of a succeedingnegative going negative g pulse between conductors d. Upon theappearance of such a succeeding negative going vertical pulse uponcontrol electrode |89, the device |85 is again driven beyond cutoff andcontinues in that kfashion so long as` pulses `appear between conductors40 with the exception of very short times just preceding each of thepulses between conductors 49. Average current flow through conductors 6|during this time is therefore extremely small and the relay 62 connectedwith conductors 5| is made insensitive to such small average current.

After the disappearance of pulses between conductors Q9, and slightlybefore the time when a Ysucceeding vertical pulse would have appeared,device |85 begins to conduct and reverse operationtakes place to causedevice I 84 to become non-conductive and device |05 fully conductive sothat maximum current flows steadily through conductor 6! The ungrcundedone of conductors 49 is also connecte-d through a condenser ISB to thecathode |99 of a rectifying discharge device, the anode 200 of which isconnected through a resistance 20| to ground.

l The cathode resistance 202 |95 is also connected through a to groundand a condenser 203 is connected in shunt with resistance 20| so that,in the presence of negative going vertical pulses between conductors @9,rectied current flows between cathode !99 and anode 290 and a negativeaverage potential appears across resistance 20|.

A switching discharge device 20d has a control electrode 205 connectedwith the ungrounded end of resistance 20| and a cathode 200 connected toground through a lbiasing resistance 201, and also connected through aresistance 208 to the positive terminal of source 59|.V The anode 209 ofdevice 2cd. is connected through a. 10aa resistance ZIB to the positiveterminal of source i8! and also to the ungrounded one of conductors i8i.

In consequence, in the absence of vertical pulses appearing betweenconductors Q9, no voltage exists across resistance 20| and resistances20? and 202 are so proportioned that the switching discharge device 204passes substantial discharge current through resistance 2li). Upon theappearance of vertical pulses between conductors 49, rectified negativevoltage with respect to ground appears across resistance 20| ofsuilcient magnitude to cut oilD current flow through device 204 so thatanode 209 rises in potential. This rise in potential, which is impressedthrough resistance |32 and condenser |83 in Figure 4 on controlelectrode il? of device |53,'immediately causes device i553 to becomeconductive at the same time pulses appear between conductors 49 and thefrequency divider of Figure 4 begins operation at that point. When thevertical lil pulses disappear between conductors 49, voltage disappearsacross resistance 20| and current iiow is initiated through device 20,the resistors 201 and 20S being properly proportioned to that end sothat anode 209 drops in potential with the result that a negative pulseis impresesd on control electrode Vi of discharge device |63, causing'it to become .and remain nonconductive, as is desired upon thedisappearance of vertical pulses on conductors 49.

The vertical yoke reversing Vrelay 62, which, as shown in Figure l, isconnected between the conductors 63 and the conductorsd, is illustratedin detail in Figure 6. As is shown, conductors 6| are connected to theterminals of a relay coil 2H whose armature 2|2 is arranged to move themovable contacts 2|3 and 2| l! of a double pole, double throw switch. Aspring 2| 5i is provided to resist attraction ofthe armature 2|2 by thecoil not carrying current, the movable contacts 2| 3t and 2M are in thelowermost position. When the coil 2| i carries current the two movableconthe two movable contacts 2|3 and 2id and the two conductors 63 (shownin Figure 1 as connected to the vertical and horizontal sweep andsynchronizing' signal generators le), are connected, respectively withthe two intermediate fixed contacts of the double pole double throwswitch and with the two outermost fixed contacts. Operation of themovable contacts 2|3 and 2M, therefore, in either direction reverses theconnection between conductors 63 and Sil, thereby reversing the polarityof the vertical sweep current passing through these conductors andthrough the vertical sweep coils 2Q, shown in Figure 1, andconsequently, turning the picture upside down or rightside up as thecase may be.

The delay blocking oscillator 55 is shown in detail in Figure 7. Thisoscillator functions to produce a steep sided pulse wave form whoseleading edge coincides with the leading edge of horizontal synchronizingpulses transferred to this oscillator through conductors 5d from thevertical and horizontal sweep and synchronizing signal generators i9 inFigure 1. One of the conductors 54 is grounded and the other isconnected through a condenser 2|i to one terminal of a resistance 2|? ofwhich the other terminal is grounded rlhe ungrounded terminal ofresistance 2|? is connected serially through an inductance coil 258 anda coupling condenser 2|9 to the control electrode 22@ of an electrondischarge device 22|, the cathode 222 of 'which is connected 'through aresistance 223 to ground. The control electrode 220 is also connectedthrough a relativelydarge grid resistance 222 and through a relativelysmall variable resistance 225 to ground. The anode'22'5 of device 22| isconnected serially through an inductance 221 (which is magneticallycoupled to inductance coil ZIB in the proper sense to cause oscillationsof the device 22|) and a variable resistance 22S to the positiveterminal of a source 229 of operating current for the device 22|, thenegative terminal of source 22a being grounded.

The circuit arrangement shown is that of a normal blocking oscillatcr,the variable resistance 225 being adjustable to adjust the blocking rateof the oscillator so that it is substantially equal to the rate ofrecurrence of pulses appearing on the conductors 54.

2|| so that, when the coil 2H is Resistance 228 is made adjustable asindicated bythe label Width equal in transmitter and receiver to adjustthe width of the steep sided pulses produced in `order that the width ortime duration of each pulse produced .by the blocking oscillator 55shall be a relatively small percentage of the total horizontal sweeptime, such width for example being in the order of 3% of the horizontalsweep time.

Conductors 56 are connected directly across I resistance 223 so that thesteep sided narrow pulses produced by the oscillator, which oi' `courseappear across resistance 223, are trans- The control electrode 23| isconnected through a grid resistance 235 to ground and the anode 236isconnected through a load resistance 231 to the positive terminal of asource 233 of operating current, the negative terminal of which sourceis grounded.

A second electron discharge device 239 has its cathode 249 connecteddirectly with cathode 233 and its control electrode 24| connectedthrough a grid resistance 242 to ground and also through a couplingcondenser 243 to the ungrounded one of conductors in Figures 1 and 4,are connected with irequency divider 5|). The anode 24.4 of device 239is connected through a load resistance '245 to the anode 236 of device232.

When vertical pulses are not present on conductors 43 in Figure fl, andthe anode |31 of the discharge device |63 in the frequency divider 59 isat a high positive potential, the control electrode 24| of device 239 isnear ground potential so that device 239 is conducting. 1n such case,the short steep sided pulses ,appearing between conductors 56 from thedelay blocking oscillator 5 are impressed on control electrode 23| andhence appear on both of the cathodes 233 and 24B whereby the anode 244of the device 239, varies in potential much more than the anode 236 ofthe device 232, and in the opposite phase. That is, the positive pulseappearing between conductors 56 during such times causes an increase inpotential of cathode 245 and a corresponding increase in potential ofanode 2443 much greater than the decrease in potential of anode 236 sothat the net potential change on anode 244 is in the positive direction.

At subsequent times when the frequency divider 52 is operating, andanode I6? of device |63 drops in potential, control electrode 22| cutsoff current flow through device '239 and ampliiication of the pulsesbetween conductors 5G is produced only through device 232. In such case,positive going narrow pulses between conductors 56 decrease thepotential oi anode 2351 which, by reason of its connection throughresistance 245 with anode 244 at the same time decreases the potentialof anode 264.

Condenser 243 must be large in order that the time constant of thatcondenser and its associated resistances shall be large compared to theperiod of pulses appearing between con- 52 which, as shown 'l5 ductors52 irornthe.anodebllA of thesdevice v|63 inthe frequency divider 52. Inother'words, discharge device. 239 must remain cut oli entirelythroughout each period when the anode |61. of device |63 isat reducedpotential.

In summary, when there is no voltage between conductors 52, pulsesbetween conductors V 56 appear in the same polarity onV conductor: 51which .is connected with anode 244 of device 239, and when a negativepotential pulse appears between conductcrs 52 to out oli the flow ofdischarge current through device 239,v positive pulses betweenconductors 56 appear inverted as negative pulses on conductor 51. Itshould be noted that only one conductor 51 is shownin Figure 8 since theother conductor 51 shown in Figure llmay be grounded and is thereforeillustrated as ground in Figure 8. w

The anode 244Y of device 239 is connected through conductor 51 and thenthrough a series combination of a condenser 246 and a resistance 241 toground, the time constant. of the v,condenser 246 and the associatedresistances being small as indicated by the label Diferentiatingcircuit. VIn consequence, positive or negative going pulses appearing onthe conductor 5,1 appear across the resistance 241 only as extremelyshort positive going pulses corresponding to the leading edge of apositive pulse on conductor 51 and extremely short negative going pulsescorresponding to the trailing edge of positive pulses on conductor 51,or vice versa.

The blocking oscillator 58 shown in Figure 1 is illustrated in detail inFigure an electron Vdischarge device 248, whose anode is connectedthrough an inductance 249 with the positive terminal of source 238. Asecond inductance 259, magnetically coupled with the inductance 249, hasone terminal connected to the control electrode 25| or device 248 andthe other terminal connected to a point between condenser 246 andresistance 241. The cathode of device 248 is grounded and the controlelectrode 25| is connected through a relatively large xed resistance 252and a relatively small adjustable resistance 253, in series, to ground.Extremely short positive pulses appearing across resistance 241 triggerthe discharge device 248, provided the adjustable resistance 253 iscaused to make the blocking rate of the oscillator substantially equalto the recurrence rate of the narrow pulses appearing across` resistance241.

Since the blocking oscillator 58 including dis.- charge device 248should not be tripped to cause an output pulse between its controlelectrode 25| and its cathode until the appearance of an extremelynarrow positive pulse across resistance 241, the resistance 253 shouldbe adjusted so that the blocking rate is somewhat lower than the rate:of recurrence of positive pulses across resistance 241.

The rate of recurrence of positive pulses across resistance 241 dependson the presence or absence of voltage'between conductors 52, sincehorizontal pulses appearing between conductors 56 appear on conductor 51either in upright or inverted phase depending on the presence or absenceof potential between conductors 52. When pulses appear on conductor 51with such polarity that the leading edge produces a positive pulseacross resistance 241, the blocking oscillator 424 fires earlier than itdoes when pulses on conductor 51 arenegative going, since the positivepulse across resistance 241 in that case corresponds with the 8, andincludes y trailing edge of the negative going pulse on conductor 51.

In consequence, horizontal scanningof the picture is caused to beginsooner or later in correspondence with the absence or presence ofVoltage between conductors 52.

The result of the arrangement shown in Figure 1, and the followingdescribed figures is to produce a television signal which is altered atV`random times in two different manners. Y

For certain intervals the television signal is not altered at all, whilein alternate intervalsA the television signal is altered both by havingits Video information turned upside down and recurrently moved back andforth horizontally. in time and by an amount corresponding to theadjustment of resistance 228 of the delay blocking oscillator 55 shownin Figure 7. The recurrent change of timing produced by the delayblocking oscillator 55 and inverter switch 53, as described, in eifectproduces a recurrent change in the time relation between video signalson the one hand and horizontal synchronizing pulses and horizontalpedestals on the other hand. It is, however, entirely within the scopeof the invention to produce that recurrent change in time rate betweenthe horizontal synchronizing signals on the one hand and the videosignals and horizontal pedestals on the other hand.

It is similarly within the scope of the invention to alter the timerelation between the vertical synchronizing signals and the 'remainderof the picture signal.

While the arrangement has been described specifically as connected witha telephone network, for convenience in channeling the tone frequencysignal to the desired locations, it is necessary only that the tonefrequency signal be channeled over some wire connection to the pointwhere the signal is desired to be used, and that some means be providedfor indicating the times when the tone frequency signal on such wireconnection is being used. Ihat is, it is entirely within the scope ofthe invention to transmit the tonefrequency signals over 60 cycle powermains from which it may be taken and used in the receiver to reconstructthe picture received over the air, suitable meters being arranged toindicate for each receiver how long the tone frequency signal currentflows from the power line to that particular receiver.

Furthermore, it is within the scope of the invention to transmit thetone frequency signal by modulating it on a carrier wave conductedthrough wire lines, where preferable.

In Figure 9 a receiver is illustrated suitable for receiving andreproducing the signal transmitted by the transmitter of Figure 1. Inthis receiver many of the elements are utilized as shown in Figure 1 anddescribed in detail in relation to Figures 2 through 8. Throughout thisapplication, like reference numerals are applied to similar elementsillustrated in diiferent figures. A tuner and detector 254 is connectedwith an antenna 255 to receive, tune and detect radiated signals, andthe output is amplified through a video amplifier 256 and impressedbetween the grid and the cathode of a kinescope or picture tube 251. Theoutput of the tuner and detector 252 is also impressed on thesynchronizing signal separator 258 constructed in usual fashion, thesynchronizing signals from the synchronizing signal separator being thenimpressed on a vertical sweep generator 259 of normal construction.

Horizontal synchronizing signals from the sepa- 18 rator 258 areimpressed through conductors 54 on the delay blocking oscillator 55which is connected in exactly the same fashion as shown in Figures 1through 8 with an inverter switch 53. a horizontal sweep blockingoscillator 58 and a horizontal sweep drive 59, which is connected withhorizontal sweep coils 250 associated with the kinescope 251 to causehorizontal traces and retraces of the electron beam in the kinescope251.

is connected a speech pass The central switchboard 22 through atelephone line 2d! with filter 252 and in turn with a telephone set 253,w

the speech pass filter :1352 being arranged to eX- clude from thetelephone set 253, tone frequency signals appearing on the telephoneline 251.

The sharply tuned amplifier and rectier 45 is connected throughconductor d tothe telephone line 251 so that it amplies and rectifiesthe tone frequency signal while excluding speech telephone signalsintended for the telephone set 283, and operates the vertical pulse gate41 through conductors 4S. Conductors 28 of vertical pulse gate 41 areconnected with the vertical sweep generator 255 from which verticalblanking pulses are transmitted to the vertical pulse gate 51, insteadof vertical synchronizing pulses as was the case in the transmitter.Gated vertical blanking pulses are transferred from gate 41 throughconductors 49 to frequency divider 50 and the relay current switch 5|.The relay current switch 5l in the presence of the gated verticalblanking pulses operates the vertical yoke reversing relay 62 throughconductors 5| to reverse the polarity of the sweep current fromgenerator 259 transmitted through conductors 53 and to the verticalsweep coils 254 associated with the kinescope 251. Pulses of dividedfrequency from the divider 5i! are transmitted through conductors 52 tothe inverter switch 53 to operate it in the same fashion as in thetransmitter, and the frequency divider 5l) is connected throughconductors i5! to the relay current switch 5l in the same fashion as inthe transmitter to cause the frequency divider to operate the inverterswitch 53 in the proper fashion at the end of each interval of itsoperation.

Because the circuit arrangements utilized in the receiver for realterlngthe picture signals to reproduce the picture correctly are substantiallya duplicate of the circuit arrangements used in the transmitter to alterthe picture signals origiarrangement, a television camera 218 containsthe usual lens system 211 for focusing an image upon an iconoscope orimage orthicon 212 which is provided with the usual vertical scanningcoil 213 and horizontal scanning coil 212. Video signals developed bythe iconoscope 212 are amplied through a video amplifier 215 and aresubsequently transmitted through a synchronizing signal and pedestalmixer 216 in which appropriate pedestals and synchronizing signals areadded to the video signals to produce the desired Ain which the programV235 to a horizontal sweep program signals. The program signal is thentransmitted to a background reinsertion device 21? to a carrier wavegenerator and vmodulatorl signal, appropriately adjusted as tobackground level, is modulated on a carrier wave which is radiated froman antenna 2W.

Normal vertical and horizontal synchronizing signals and normal verticalsweep signals are generated by vertical and horizontal sweep andsynchronizing signal generators 288 and are impressed respectively onconductors 28| and 282, which conductors are connected respectively withthe synchronizing signal and pedestal mixer 216 and the verticalscanning coils 213 associated with the iconoscope 2112. The horizontalsignal is fed from the vertical and horizontal sweep and synchronizingsignal generators 280 through conductors 283 to a delay line and switch284, from which such signals altered in accordance with the inventionare then fed through conductors drive 288 of normal construction, andfrom thence through conductors 282i to the horizontal sweep coils 274associated withthe iconoscope 2l2. In order to perform the desiredalterations of the horizontal signal in the delay line and switch 284 atproperly timed intervals, positive going vertical pulses from thevertical and horizontal sweep and synchronizing signal generators 289are impressed through conductors 283 on a frequency divider 2s@ whichproduces on conductors 28E pulses of lower frequency than the positivegoing vertical pulses from generators 28B. Such lower frequency pulsesare impressed through conductors 29| on a tone frequency oscillator 292which produces alternate bursts of oscillations of source frequencysuitable for transmission by wire line conductor to receivers. Thesebursts of oscillations coincide in time with the lower frequency ypulses, existing only when such lower frequency pulses are of onepolarity. These bursts of tone frequency oscillations are impressed onconductors 283 which are connected to a central switchboard 295i in thesystem of wire line conductors, which may be, for example, connected ina telephone system.

Conductors 299 are connected with conductors 293 at one end and at theother end are connected to supply such tone frequency oscillations to atone frequency filter and switch operator dit, which is also suppliedwith positive going vertical pulses from conductors 288 throughconductors il l. This tone frequency filter and switch operator, in thepresence of such tone frequency oscillations, utilizes the positivegoing vertical pulses to impress pulses balanced with respect to groundon conductors 290, the frequency of such balanced pulses being asubmultiple of the vertical pulses on conductors 288, The balancedpulses on conductors 29s are impressed on the delay line and switch 284to cause it to change the timing of horizontal pulses passing fromconductors 283 to conductors 285 during recurrent intervals whosefrequency is a submuitiple of the vertical pulses from the generators2353.

Accordingly, at each time when a change is made in the transmission ofhorizontal pulses from conductors 283 through the delay line and switch284 to conductors 285, such change is indicated as may be desired,either by the presence 4or absence on the telephone line conductors 293rfg the tone frequency oscillations from oscillator ode 3D1 of deviceages from generators 285 are mixed Ythe other discharge device Asexplained in connection with Figures l through 9, such tone frequencyoscillations on the telephone conductors 293 are transmitted by thoseconductors to a central switchboard 29rd from which the oscillations maybe distributed upon making a charge therefore to any subscriber whodesires the service. Also as previously explained, the conductors 283while illustrated as forming a part of the telephone system may insteadbe connected with power lines in connection with which provision is madefor making a charge to a subscriber whenever tone frequency oscillationsare taken from such lines.

When, in the arrangement of Figure l0, an iconoscope requiring shadingvoltages is used in camera 21), it is desirable that the shadinggenerators be sup-plied with normal vertical synchronizing signals fromgenerators 282 and with horizontal synchronizing signals from the delayline and switch 282i. For this purpose, a rectangle 295 is illustratedbearing the label Shading generators, connected with the vertical andhorizontal sweep and synchronizing signal generators 288 throughconductors 298, and connected with conductors 2&5 through conductorsZtl. The shading generators 25E may be of any standard type capable ofproducing both vertical and horizontal shading voltages as required,provided the horizontal shading voltage generators have a sufficientlyshort time constant to change phase within the time of one or twohorizontal lines when the phase of horizontal synchronizing signais onconductors 285 changes.

The mixed horizontal and vertical shading voltwith the composite signalin the mixer 2%, to which they are supplied through conductors 293.

In Figure 11 the circuit details of the frequency divider 28g areillustrated, although that frequency divider is very similar in mostrespects to one of the two frequency dividers illustrated in Figure 4.It is, however, necessary in the a1'- rangement of Figure 10 only tohave the 'frequency divider 289 operate at any desired submultiplefrequency `of the frequency of positive going ver tical pulses onconductors 2st.l

In this gure the frequency division is accomplished by the connectiono'f two electron discharge devices 388 and Sill in such a way that oneremains conductive and the other remains nonconductive until theappearance between "conductors 288 'of the positive going pulse, afterwhich becomes conductive and the one remains non-conductive until thesubsequent appearance of another positive pulse between 'conductorsl'288. While the frequency divider illustrated in Figure ll is capableof producing pulses on conductors 29 whose frequency is one-half that ofthe frequency of pulses on conductors 288, it is a very simple matter toproduce pulses yof any other desired in'te'gra1 frequency relation bythe inter-position in conductors 288 of one or more cascade connectedblocking oscillators of the type illustrated in Figure '7, 'adjusted toincrease or decrease the pulse frequency as desired.

As illustrated, one of the 'conductors 288 is connected to ground andone 'of conductors 28E is connected to ground, the ungrounded one 'ofconductors 288 being connected through a series combination of acondenser 382 and a resistance 323 to the control electrode Sil@ ofdevice elle. A grid resistance 385 is connected between controlelectrode 384 and ground and the cathode 3BG of device 308 'isAconnected directly with the cathv(till, both cathodes being con-

